On Tue, Feb 01, 2000 at 11:18:01PM +0000, Russell King wrote:
> Hi,
>
> I've just had a report that I've confirmed that /dev/random on ARM doesn't
> behave the same as /dev/random on x86.
>
> I've confirmed this by comparing a NetWinder with an IBM thinkpad. Both these
> have PS/2 mice. The NetWinder is running 2.3.41, which uses the standard
> random.c and pc_keyb.c sources. The thinkpad is running untouched 2.2.12 at
> the moment.
>
> On the thinkpad, doing an 'od -t x1 -Ax /dev/random' and moving the mouse in
> a console results in a lot of bytes being generated from the device. However,
> on a NetWinder, it results in very few, less than 1/10th of what the x86
> machine produces.
>
> I have also compared it with other ARM architectures (on 2.2.14) use the
> busmice code (which got added to 2.3 iirc) to add randomness, and that behaves
> in the same manner as the NetWinder.
>
> Does anyone have any clues what might be causing this odd behaviour? I haven't
> scanned over random.c in any great depth yet.
Yes. The random driver on i386 uses the current cycle counter on Pentium+
machines for a few extra bits of randomness. Unfortunately, this is not
implemented for other architectures. There was a discussion about this a few days
ago concerning the alpha.
dave...
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This archive was generated by hypermail 2b29 : Mon Feb 07 2000 - 21:00:07 EST